What Is the Indigestible Food That Helps to Stimulate the Digestive System Called?

Whole-wheat bread provides dietary fiber.

If you're looking for a way to stimulate your digestive system without adding a lot of calories to your diet, eat more foods high in fiber. While you can't digest fiber, it has a number of effects in your digestive tract and may help lower your risk for high cholesterol, heart disease and digestive complaints like constipation. Women should aim to get 21 to 25 grams per day and men need at least 30 to 38 grams.

Soluble versus Insoluble Fiber

Aim to eat a variety of different fiber-containing foods so you get a mix of soluble and insoluble fiber. Soluble fiber, which forms a gel when combined with liquid, has different effects on your digestive system than insoluble fiber, which adds bulk to your stool. Soluble fiber is the type of fiber known for beneficial effects on cholesterol and blood sugar levels, while insoluble fiber has the most benefits for lowering your risk for digestive complaints.

Effect on Digestion

The gel formed by the combination of soluble fiber and liquids slows the separation of liquids from solids in the stomach, and thus the emptying of the stomach and the release of sugars into the bloodstream. This helps you feel full for longer. Once the partially digested food leaves the stomach, the added bulk from insoluble fiber helps cause the intestines to contract, moving your stool through the digestive process more quickly. Fiber can trap some nutrients and prevent them from being absorbed in the small intestine, but the effect is minimal if you eat a variety of healthy foods. Bacteria in your intestines then ferments some types of fiber, providing your body with some nutrients and partially breaking down the fiber, but this can also cause bloating due to the gases created during the process.

Effect on Transit Time

A combination of soluble and insoluble fiber helps improve the transit time of food going through your digestive tract. The soluble fiber helps make your stool softer and moister, which means it can travel between 32 and 100 times faster through your digestive tract than a dryer, harder stool, according to "Spinal Cord Medicine: Principles and Practice." The effect of insoluble fiber depends on the type, with lignin and cellulose being the most likely to speed up transit time.

Fiber Sources

Foods containing soluble fiber include oats, legumes, barley, fruits, vegetables, nuts and seeds. To increase your insoluble fiber intake, eat more whole grains and vegetables. You can also take fiber supplements, but its better to get your fiber from foods, as these provide other nutrients as well as just fiber. Increasing your fiber intake too rapidly or without also increasing your water intake could cause adverse effects, including bloating, gas or abdominal cramps.